[616-47-7] · C4H6N2 · N-Methylimidazole · (MW 82.12)
Physical Data: bp 195-197 °C; d 1.031 g cm-3.
Solubility: usually used in THF, Et2O.
Form Supplied in: redistilled liquid (99+%); packed under nitrogen.
Analysis of Reagent Purity: the reagent may be analyzed using standard techniques.
Purification: dried with sodium metal and then distilled.
Handling, Storage, and Precautions: store at 0 °C under dry argon. The compound is harmful in contact with skin and if swallowed, and causes burns.
N-Methylimidazole is used for phosphorylation and acylation. It can be lithiated at the 2-position by treating with n-Butyllithium at -78 °C in THF or diethyl ether. The Grignard reagent can also be prepared by exchange with Ethylmagnesium Bromide at the 2-position.1
Alcohols may be phosphorylated in good yield by the reaction of phosphorous acid, mercury(II) chloride and N-methylimidazole (eq 1). An intermediate salt (1) is formed. This method has been used to prepare nucleoside 5´-phosphates in yields of 60-70%.2 Similarly, amines may be phosphorylated by reaction with Phosphorus Oxychloride and N-methylimidazole (eq 2).3
N-Methylimidazole reacts with acid chlorides and chloroformates to give N-acylimidazolium salts. These can then be used as effective acylating agents, for example of amines, in aqueous solution (eq 3).4
N-Methylimidazole has been used as an effective catalyst of acylation by Acetic Anhydride. It has a catalytic activity about 4 × 102 greater than pyridine (eq 4).5
2-Lithio-1-methylimidazole reacts with ketones at -78 °C in 65-96% yield to give 2-(1-hydroxyalkyl)-1-methylimidazoles. These can be dehydrated with hot acetic anhydride to give 2-vinyl-1-methylimidazoles in 73-85% yield (eq 5).6
2-Lithio-1-methylimidazole reacts with alkyl or aryl nitriles to give 2-acyl-1-methylimidazoles (acid anhydrides, acid chlorides and amides give poor, nonreproducible yields of the ketones). These then yield 1-methylimidazolethylenes via a Wittig reaction. Vinylimidazoles are reported to be potentially useful as monomers in the synthesis of heterocyclic polymers (eq 6).7
2-Imidazolylsilanes may be synthesized by reacting Chlorotrimethylsilane with 2-lithio-1-methylimidazole and subsequent transsilylation (eq 7).8
University of Bristol, UK